A Policy Guide to Steel Moment-frame Construction

A Policy Guide to  Steel Moment-frame Construction

A Policy Guide to  Steel Moment-frame Construction

SAC is a joint venture of the Structural Engineers Association of California (SEAOC), the Applied Technology Council (ATC), and California Universities for Research in Earthquake Engineering (CUREe),formed specifically to address both immediate and long-term needs related to solving performance problems with welded, steel moment-frame connections discovered following the 1994 Northridge earthquake.

SEAOC is a professional organization composed of more than 3,000 practicing structural engineers in California. The volunteer efforts of SEAOC’s members on various technical committees have been instrumental in the development of the earthquake design rovisions contained in the Uniform Building Code and the 1997 National Earthquake Hazards Reduction Program (NEHRP) Recommended Provisions for Seismic Regulations for New Buildings and Other Structures. ATC is a nonprofit corporation founded to develop structural engineering resources and applications to mitigate the effects of natural and other hazards on the built environment. Since its inception in the early 1970s, ATC has developed the technical basis for the current model national seismic design codes for buildings; the de-facto national standard for post earthquake safety evaluation of buildings; nationally applicable guidelines and procedures for the identification, evaluation, and rehabilitation of seismically hazardous buildings; and other widely used procedures and data to improve structural engineering practice. CUREe is a nonprofit organization formed to promote and conduct research and educational activities related to earthquake hazard mitigation.
CUREe’s eight institutional members are the California Institute of echnology, Stanford University, the University of California at Berkeley, the University of California at Davis, the University of California at Irvine, the University of California at Los Angeles, the University of California at San Diego, and the University of Southern California. These university earthquake research laboratory, library, computer and faculty resources are among the most extensive in the United States.

The SAC Joint Venture allows these three organizations to combine their extensive and unique resources, augmented by consultants and subcontractor universities and organizations from across the nation, into an integrated team of practitioners and researchers, uniquely qualified to solve problems related to the seismic performance of steel moment-frame Structures.
The Northridge earthquake of January 17, 1994, caused widespread building damage throughout some of the most heavily populated communities of Southern California including the San Fernando Valley, Santa Monica and West Los Angeles, resulting in estimated economic losses exceeding $30 billion. Much of the damage
sustained was quite predictable, occurring in types of buildings that engineers had previously identified as having low seismic resistance and significant risk of damage in earthquakes. This included older masonry and concrete buildings, but not steel framed buildings.

Surprisingly, however, a number of modern, welded, steel,moment-frame buildings also sustained significant damage. This damage consisted of a brittle fracturing of the steel frames at the welded joints between the beams (horizontal framing members) and columns (vertical framing members). A few of the most severely damaged buildings could readily be observed to be out-of-plumb (leaning to one side). However, many of the damaged buildings exhibited no outward signs of these fractures, making damage detection both difficult and costly. Then, exactly one year later, on January 17, 1995, the city of Kobe, Japan also experienced a large earthquake, causing similar unanticipated damage to steel moment-frame buildings.

No comments
Post a Comment

    Reading Mode :
    Font Size
    lines height